program experiment

    implicit none
    
    type link
        character ::c
        type(link),pointer::next
    end type link
    type(link),pointer::root,current
    
    integer::io_stat_number=0
    
        allocate(root)
        read(*,'(A)',advance='no',iostat=io_stat_number)root%c
        if(io_stat_number==-1)then
            nullify(root%next)
        else
            allocate(root%next)
        endif

        current=>root
        do while(associated(current%next))
            current=>current%next
            read(*,'(A)',advance='no',iostat=io_stat_number)current%c
            if(io_stat_number==-1)then
                nullify(current%next)
            else
                allocate(current%next)
            endif
        end do

        current=>root
        [color=FF0000]do while(associated(current%next))[/color]                
            print *,current%c
            current=>current%next
        end do 
    end program experiment
    
    
    
    以上是代码  
    
    我的问题是红字处 的意思是不是说如果current%next没有关联循环就不执行
    可是最后一个（我理解是最后一个current%next应该是没关联的吧）current%c为什么还能被print呢